There is a difference, sometimes, between the PageRank shown in the Google Directory when compared to the PageRank shown in the Google Toolbar. Also, the PageRank values Google has internally are normally different from both the Directory and Toolbar PageRank values.

Gabs showed an example of a change. If you look at the cached version of this page, it shows a PageRank value of 3 for Abbey Theatre but the current version shows a PageRank value of 2 (I may be off on those numbers, but you can clearly see the current version of the PageRank bar is less than the cached or older version. Here is a side by said:

Current:

Past:

Side by side, just looking at the PageRank bars:

Note, we had a Google Directory Data Update last month, but the last time I reported a PageRank score update at the Google Directory was back in 2004, that is not saying it hasn't happened since.